[sdk-platform-java] Paged Callables are not being Traced

From gRPC's CallableFactory: https://github.com/googleapis/sdk-platform-java/blob/ba648ceac869d4fab1a9cbeb40f2e04f69dad4e3/gax-java/gax-grpc/src/main/java/com/google/api/gax/grpc/GrpcCallableFactory.java#L129-L139

Paged Callables do not have a TracedPagedCallable equivalent which implements tracing. It is possible that we can reused the TracedUnaryCallable, but that requires some investigation.

Start at GrpcCallableFactory.java around lines 129-139 and inspect how paged callables are created. Investigate whether TracedUnaryCallable can be reused, as suggested in the issue, or whether a TracedPagedCallable equivalent is needed. Done means paged callables implement tracing consistently with the other callable types.

由索引模型根据 Issue 内容生成。